1. Field of Invention
This invention relates to novel lacquer compositions which afford desirable improvements in the durability and hardness of the resulting coatings. More particularly, this invention is concerned with novel nitrocellulose-resin based lacquers which contain small amounts of both a high molecular weight mixture of water-soluble gelatins derived from animal bone and hide and an acrylic copolymer and conventional additives. The lacquers are particularly useful for human nail coatings. The novel process for preparing the lacquers involves a novel intermediate which is a solid dispersion of water-soluble gelatin in nitrocellulose.
2. Description of the Prior Art
As is generally known, various base coatings have been prepared and marketed in the past for nail surfacing and various attempts have been made to improve the general performance of coatings which have nitrocellulose as primary film-forming base.
Addition of finely particulated water-insoluble albuminoids such as keratin to nail compositions containing cellulose nitrate and natural or synthetic resins has been disclosed in U.S. Pat. No. 3,483,289.
U.S. Pat. No. 3,907,580 discloses schleroprotein derivatives having such as a collagen hydrolyzate of animal origin with a pH in the range of about 3 to 7.5 in combination with nitrocellulose and an (aryl)sulfonamideformaldehyde resin.
French Patent No. 1.572.598 utilizes an alcohol-soluble protein (collagen) which is specified to be a hydrolyzed gelatin with a molecular weight range of up to 10,000, preferably 500-1000.
The use of methacrylate resins in a cellulose nitrate based fingernail enamel composition is disclosed in U.S. Pat. No. 2,195,971.
While the incorporation of lacquer-insoluble pigments via plasticized nitrocellulose sheet is a known procedure, W. C. Doviak "Cosmetics, Science and Technology", 2nd Ed. Vol. 2, p. 528 (1972), Wiley Interscience Ed. M. S. Balsam et al., this method of dispersing water-soluble gelatin has not heretofore been disclosed.
Prior to the present invention, the joint use of a water-soluble gelatin having molecular weight ranging from 15,000 to 250,000 and an acrylic copolymer to drastically modify and improve the appearance and performance of coatings having the film formers utilized in this invention has not been disclosed. Moreover, in addition to novelty of combination, the method of preparation is also new and novel.
First trials to make a lacquer containing gelatin of the nature envisioned; i.e., water-soluble gelatin of molecular weight 15,000-250,000 derived from a mixture of bone and hide, in combination with the acrylic copolymer met with failure when known methods of incorporating and dispersing collagenous materials of the prior art were applied. To sum up these unsuccessful attempts, the water-soluble gelatin always settled out of the lacquer even after the most vigorous and efficient types of stirring were employed.
As a result of persistent efforts and consideration, methods were found to carry out this invention. These methods utilize high shear grinding of the water-soluble gelatin. This dispersion of gelatin, which is colloidal in nature, can be obtained by conventional means for forming colloid suspensions such as by the use of ball mills or on roller mills. The gelatin is predispersed in the solvents, resins, and plasticizers, which are used in the formulation. One method used to carry out the invention employs coplasticizing in intimate admixture the water-soluble gelatin having a particular molecular weight range and derivation and the nitrocellulose. Preparation of the lacquer of this invention requires predispersion of the gelatin, believed to be of colloidal size, in solid plasticized nitrocellulose mass, a procedure not previously known in the art.